Submission #910051

#	Time	Username	Problem	Language	Result	Execution time	Memory
910051		Denisov	One-Way Streets (CEOI17_oneway)	C++14	100 / 100	148 ms	32216 KiB

oneway

//#pragma GCC optimize("Ofast", "unroll-loops")
//#pragma GCC target("sse", "sse2", "sse3", "ssse3", "sse4")

#include <bits/stdc++.h>

#define all(a) a.begin(),a.end()
#define len(a) (int)(a.size())
#define mp make_pair
#define pb push_back
#define fir first
#define sec second
#define fi first
#define se second

using namespace std;

typedef pair<int, int> pii;
typedef long long ll;
typedef long double ld;

template<typename T>
bool umin(T &a, T b) {
    if (b < a) {
        a = b;
        return true;
    }
    return false;
}
template<typename T>
bool umax(T &a, T b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}

#ifdef KIVI
#define DEBUG for (bool _FLAG = true; _FLAG; _FLAG = false)
#define LOG(...) print(#__VA_ARGS__" ::", __VA_ARGS__) << endl
template <class ...Ts> auto &print(Ts ...ts) { return ((cerr << ts << " "), ...); }
#else
#define DEBUG while (false)
#define LOG(...)
#endif

const int max_n = 1e5 + 11, inf = 1000111222;


struct ed {
    int to, id;
};

vector <ed> edge[max_n], g[max_n];

int used[max_n], bridge[max_n], tin[max_n], timer = 1, low[max_n];

inline void dfs (int v, int p = -1) {
    used[v] = 1;
    tin[v] = low[v] = timer++;
    for (auto &e : edge[v]) {
        int to = e.to, id = e.id;
        if (id == p) {
            continue;
        }
        if (used[to]) {
            umin(low[v], tin[to]);
        }
        else {
            dfs(to, id);
            umin(low[v], low[to]);
            if (low[to] > tin[v]) {
                bridge[id] = 1;
            }
        }
    }
}

int cmp[max_n];

inline void color (int v, int c) {
    used[v] = 2;
    cmp[v] = c;
    for (auto &e : edge[v]) {
        int to = e.to, id = e.id;
        if (used[to] == 1 && !bridge[id]) {
            color(to, c);
        }
    }
}


int up[max_n], down[max_n];

int res[max_n], d[max_n];


inline void go (int v, int p = -1) {
    used[v] = 4;
    for (auto &i : g[v]) {
        int to = i.to, id = i.id;
        if (to == p) {
            continue;
        }
        d[to] = d[v] + 1;
        go(to, v);
        if (up[to]) {
            res[id] = 1;
        }
        if (down[to]) {
            res[id] = 2;
        }
        up[v] += up[to];
        down[v] += down[to];
    }
}


int L = 0, T = 0;
vector <int> upp[max_n];
int tin1[max_n], tout[max_n];

inline void dfs_lca (int v, int p = -1) {
    tin1[v] = T++;
    used[v] = 3;
    upp[v].resize(L + 1);
    upp[v][0] = p == -1 ? v : p;
    for (int i = 1; i <= L; i++) {
        upp[v][i] = upp[upp[v][i - 1]][i - 1];
    }
    for (auto &i : g[v]) {
        int to = i.to;
        if (to == p) continue;
        dfs_lca(to, v);
    }
    tout[v] = T;
}

inline bool upper (int a, int b) {
    return tin1[a] <= tin1[b] && tout[b] <= tout[a];
}

inline int lca (int a, int b) {
    if (upper(a, b)) return a;
    if (upper(b, a)) return b;
    for (int i = L; i >= 0; i--) {
        if (!upper(upp[a][i], b)) {
            a = upp[a][i];
        }
    }
    return upp[a][0];
}


int main() {
//    freopen("input.txt", "r", stdin);
//    freopen("output.txt", "w", stdout);

    ios_base::sync_with_stdio(0);
    cin.tie(0);

    int n, m, p;
    cin >> n >> m;
    while ((1 << L) <= n) ++L;
    vector <pii> e(m);
    for (int i = 0, a, b; i < m; i++) {
        cin >> a >> b;
        --a, --b;
        e[i] = {a, b};
        edge[a].pb({b, i});
        edge[b].pb({a, i});
    }
    cin >> p;


    for (int i = 0; i < n; i++) {
        if (!used[i]) {
            dfs(i);
        }
    }

    int num = 0;
    for (int i = 0; i < n; i++) {
        if (used[i] == 1) {
            color(i, num);
            ++num;
        }
    }

    for (int i = 0, j = 0; i < m; i++) {
        int a = cmp[e[i].first];
        int b = cmp[e[i].second];
        if (a != b) {
            g[a].pb({b, j});
            g[b].pb({a, j});
            ++j;
        }
    }

    for (int i = 0; i < num; i++) {
        if (used[i] == 2) {
            dfs_lca(i);
        }
    }

    for (int i = 0, a, b; i < p; i++) {
        cin >> a >> b;
        --a, --b;
        a = cmp[a];
        b = cmp[b];
        if (a == b) {
            continue;
        }
        int v = lca(a, b);
        down[a] += 1;
        down[v] -= 1;

        up[b] += 1;
        up[v] -= 1;
    }

    for (int i = 0; i < num; i++) {
        if (used[i] == 3) {
            go(i);
        }
    }

    for (int i = 0, j = 0; i < m; i++) {
        int a = cmp[e[i].first];
        int b = cmp[e[i].second];
        if (a != b) {
            if (res[j] == 0) {
                cout << 'B';
            }
            else if (res[j] == 1) {
                if (d[a] < d[b]) {
                    cout << 'R';
                }
                else {
                    cout << 'L';
                }
            }
            else {
                if (d[a] < d[b]) {
                    cout << 'L';
                }
                else {
                    cout << 'R';
                }
            }
            ++j;
        }
        else {
            cout << 'B';
        }
    }
    cout << '\n';
}

• Subtask 1: 30 / 30
• Subtask 2: 30 / 30
• Subtask 3: 40 / 40